Brake



g 39- L. E. LA IBRIE 2,167,721

BRAKE} Original Filed Nov. 22, 1930 INVENTOR Q LUDGEQ Elk-x1512? ATTORNEY.

Patented Aug. 1, 1939 BRAKE,

Detroit, Mich, minor to Ludger a; u Brie,

FICE

Bendix Brake Company, South Bend, Ind, a. corporation of Illinois Original application November 22, 1930, Serial No. 497,383, now Patent No. 2,095,752, dated October 12, 1937, Divided and this application July 2'], 1936, Serial No. 92,798

2Claims.

This invention relates to inches, and is illustrated as embodied in a novel system of hydraulic brakesfor an automobile.

it will be appreciated that the presence oi any a substantial amount of air in the lines of a hydraulic brake system renders the system almost inoperative, as all of the brake-applying movement of the parts is then taken up idly in compressing the air. The great advantages of a it hydraulic brake system depend to a great extent on the non-compressibility oi the operating liquid.

One object of the invention is to provide means to eliminate air from the system and to prevent i its re-entry.

Features of the invention relate to the construction of the wheel cylinders, several forms being shown. These features have to do with sealing the parts against leakage, to an arrangego ment for bleeding" the lines, i. e. filling them with liquid and getting rid of entrapped air, and to an arrangement of a two-way checlr valve in itself embodying substantial novelty, to iacilitate the "bleeding.

w The above and other objects and features oi the invention, including various novel and desirable details of construction, will be apparent from the following description of the illustrative embodiments shown in the accompanying drawing,

pp in which:

Figure l is a top plan view oi part of an automobile chassis showing the arrangement oi the parts of a system of hydraulic brahm;

Figure 2 is a section through the cylinder at my the brake h showing the connection thereto oi the hose coupling or the like from the operating lines, and illustrating particularly the, arrangement of a two-way check valve used in bleedim the line; and

Figures 3 and 4 are sections through fittings containing dliferent types of two-way checlr .valves which may be substituted tor the one shown in Figure 2.

The chassis shown in Figures l and 2 includes dd the usual chassis frame lill supported by the usual springson front and rear axles (not shown) carried by front wheels 32 having brakes indicated generally at it and on rear wheels it having brakes also indicated generally at it.

to The brakes are intended to be operated by a hydraulic system including flexible hose connections 38 adjacent the four wheels and communicating by suitable pipes Ill carried by the chas sis frame 30 with the outlet it of a master cylinder assembly 44 which may be oi one of any (Cl. fill-54.6)

suitable forms and which may include an operating piston connected by a piston rod 46 with the usual brake pedal 48. The hydraulic system is kept lull of liquid by means of a reservoir M which is mounted on the dash above the master cylinder and on the opposite side of the dash irom the driver. The reservoir to is connected to the master cylinder it by means such as a flexible conduit bl.

A connection between the master cylinder and each of the wheel cylinders llil preferably includeaimmediately adjacent the wheel cylinder, a fitting ltd within which is arranged a twoway check valve which is utilized to control bleeding through a passage ltd which is normally closed by a plug threaded into an outlet opening lit. in the arrangement oi Figure 2, fitting ltt is iormed internally with a double diameter bore. Inside of the larger diameter portion of the bore is a cup-shaped piston valve l'li urged by a spring llt against a conical seat at the junction oi the small and large diameter parts of the bore. The valve member lift is formed with an opening base communicating with the small diameter part oi the bore and which is normally closed by a ball check valve llt urged thereagainst by a spring llt. When it is desired to "bleed the system to fill it with liquid or to remove air which has become entrapped therein, the plug is removed from the outlet opening lit and sumcient liquid is forced from the master cylinder and the reservoir through the various conduits lit and it to flll all the wheel cylinders ltd and pump an excess through the tour outlets llt sumcient to insure the removal of all the air. When this is being done, the ball check valve l'lt yields to permit A the passage oi the additional liquid. During the application oi. the brake, when pressure is applied to the system, liquid passes the ball checlr valve llt through opening in the base of the cupshaped valve member lit in sufilcient quantity to lorce the brake shoes against the drum. When the brake is released, the return springs force this additional liquid bachwardly, whereupon the cupshaped valve member l'll moves bacir oh its conical seat and permits the additional liquid to leak baclr around between the valve member and the large diameter part oi the bore oi the iltting ltd. in Figures 3 and i are shown two other forms of two-way chech valves which may be provided in the fitting ltd. in the arrangement of Figure 3, the cup-shaped valve member l'lt is arranged as in Figure 2, but in place of the ball check valve llt I provide another piston valve memill tilt

till

ber ill held between spring ill in a position to close the opening in the bottom of the valve member I'll. In the arrangement oi. Figure 4. a hollow valve member ill is held against the above-described conical seat between spring ill, a ballcheck valve I84 being arrangedinside oi the valve member ill and held in place lightly by a spring I;

While a number oi'illustrative embodiments oi the invention have been ducribed in detail,

it is not my intentionto limit'its scope to-these particular embodiments or otherwise than by the terms 0! the appended claims,

V The present application is a division of my application Serial No. 491,883, iiled November'22. 1930, issued as Patent No; 2,095,752 on October 12, 1937.

I claim:

1. A wheel cylinder having a bleeder outlet and having a connection to brake system conduit. in combination with a means arranged in said connection between the conduit and the cylinder for allowing substantially free passage of liquid I aim-mi irom said conduit to the cylinder and allowinl passage of fluid under substantial diiierentials in pressure from the cylinder to the conduit for maintaining a predetermined pressure upon the liquid in the cylinder.

2. A wheel cylinder having a bleeder outlet and having aninlet connection, a brake vsystem conduit connected to said inlet, in combination with a conduit fitting for connecting said wheel cylinder to said conduit formed with a pair 01' concentric communicating bores oi diii'erent diameters, the smaller bore being connected directly to the cylinder and the larger bore being 

